Circuit arrangements for monitoring short circuits and overloads for a-c switches are previously known from German application DE-AS No. 21 49 063. In particular, the output of a three-conductor proximity switch can be switched off after a delay time whenever the maximum permissable load current is exceeded and switched on again after a waiting time which is substantially longer than the delay time. The testing cycle is repeated until the overload or the short circuit condition is corrected. However, for loads which are to be switched over long transmission lines by such proximity switches, the testing cycle can be initiated even for permissable load current values if too short a delay time is chosen. This is caused by the line capacity of each conductor which is proportional to the length of the transmission line and represents, in the first instant of time, a short circuit for the proximity switch since the line capacities must be charged by the output current. Yet, if the delay time were chosen accordingly lng and a true fault condition existed, a relatively large energy loss would occur during the testing cycle, which in most cases, leads to a thermal overload of the switching elements. In order to prevent this thermal overload, the cycle or waiting time could be increased, but this, in turn, would have an adverse effect on the speed of the fault detection.